Tetrabromo derivative of indigo and process of making same.



Swiss Republic, and a resident UNITED STATES PATENT, oFFiion.

GADIENT ENGI, OF BASEL, SiYlTZERLAND, ASSlGiYOR SOCIETY OF CHEMICAL 1K DUSTRY 1N BihSlJE, 01 BASEL, b\\'1'1" .il 11'l1iAl\1). TETRABROMO DERlVATlVE OF lNDlGO AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented June 11, 1907.

Application filed March 23,1907b Serial No. 364,020.

To all whmw it 112 01 concern.-

Be it known that I, GADIEXT Exci. doctor of philosophy and chemist, a citizen of the oi Basel, Switzerland, have invented new and useful Tetrabromo Derivatives of indigo and a Process of Making the Same, of which the following is a full and exact specification.

Hitherto tetrabromo derivatives of indigo are not known. 1 have found that such tetrabromo substitution products of: indigo are produced in an extremely smooth manner and with substantially quantitative yield by treating indigo or its monoand di-bromo derivatives with suitable proportions of bromin at a raised temperature in presence of appropriate solvents or of appropriate media in which the material may be suspended. The new tetrabromo derivatives of indigo thus obtained are extremely valuable dyestuffs on account of their tinctorial prop erties, for they can be easily made into vats by the usual methods and dye cotton without a-morda-nt clear blue tints, which are considerably more vivid and of a greener shade than the tints obtained by means of indigo or its known inonoor di-bromo derivatives: moreover, as composed with the latter, they are considerably faster to washing and chlorin.

The manufacture of these new tetrabromo derivatives of indigo is illustrated by the following examples.

Example I. 5 parts 01 indigo, parts of nitro-benzene and 1618 oarts of commercial broniin are heated together in a rellux a paratus in an oil bath, the temperature of t e latter'being raised to 225 C. in the course of 1% hours and the mixture being kept in gentle ebullition for a further 1 hours. After cooling the mass the brominated product which separates in the form of voluininou's, violet' little crystals, is iiltered. washed with alcohol and dried. The dyestull' thus obtained is a tetralironic-derivative (C H O N Br 1t dissolves in concentrated sulfuric acid with a deep blue coloration and in fuming sulfuric acid containing 24 per cent. SO with a greenish blue coloration becoming pure blue on heating. On pouring this latter solution into ice-water bluishgreen flocks separate. It is hardly soluble in cold anilin and cold nitrobenzene and very sparingly soluble in hot anilin with a deep blue coloration and in hot nitrobenzene .with

blue violet coloration. it is insoluble in water and scarcely soluble in chlorol'orm. By treatment with the usual \nl media it yields a bright yellow vat. in which unmordantcd cotton is dyed last clear greenislnblue tints im-reasing in brightness and l'astness to chlorin when subjected to a short soaping or a shorttreatment with a solution of sodium carbonate at (50 t.

Example 11. A mixture ol .3 parts of indigo, 50 parts of nitrohenzene and 16 parts ol bromin is allowed to stand for 24 hours at the ordinary temperature.-and then heated in a rellux apparatus in an oil bath i'or Z--4 hours, the temperature of the bath being C. After cooling, the mass is illtered and the solid matter is washed with alcohol and dried. The d \'estull' obtained in this manner forms bluish-violet small crystals and has the composition ol a. tetrabronn indigo. (t ll O N Br l. Apart from small diilerences in the solubility in various solvents as well as in the colors of the solutions. it diil'ers from the tetrabroni-indigo obtained according to Example 1 by the dyeings on cotton which are considerably more reddish and more vivid than those obtained by means of the dyestull made according, to Example 1. The brightness and density of the dyeings are also increased by sou-ping them or treating them with a solution of sodium ca rhonate.

Instead of brominating indigo itself, the

inainnlocture of brommdigo may also be ett'ected by l'u'rther brominaling the mono or dibromo-sui stituiion products made by the known processes or the tribnaim-substitution products obtained according to my ap plication 'l'or Letters Patent executed at the same date as the present one.

Example 111. 4 parts of dibromindigo. made for example by hro ninating indigo in glacial acetic acid in the known manner. are suspended in ilk-=54) partsl niirobenzenc, i5 parts of bromin added and the mix ture is heatcdl or S' -l hours in a rcllnx apparatus so that it boils gently. Alter cooling, the separated product of the reaction is iiltered and washed with alc hol. The tetrahromindigo possesses properties similar to "ro Tl-JE rum or form, cold anilin and cold nitrobenzene, d iffi-- eultly soluble in not anilin and hot nitrobenzene with blue to blue-violet color, dissolving 1n concentrated sulfuric acid wlth deep blue color ant yielding by treatment with alkaline reducing agents a light-yellow colored vat, fTom which unmordanted cot-ton is dyed pure blue shades, fast to washing, light and 01110- rin. 1

In'witness whereof I have hereunto sigi'ied my name this 2 day of li'lerch 1907, in the presence of two subscribing witnesses.

GADIEXT EXGL Witnesses:

- GEO. GIFFORD,

AMAKD BRAUN. 

